The present invention relates to method of producing an odorless soybean milk having no smell of soybean and a method of producing tofu (bean curd) using bittern.
In the past, soybean milk has been produced by fully soaking soybeans in water, grinding the soaked soybeans, adding water to the thus ground soybeans (the resulting solution is referred to as a go-eki) and boiling and straining the go-eki through a piece of cloth.
On the other hand, bean curd has been produced by coagulating the soybean milk with bittern (the principal component is magnesium chloride) which is a coagulant and the production of bean curd has been made by a workman by hand thus still considerably retaining the character of domestic industry up to quite recently.
Because the reactivity of magnesium chloride has been so high that skill is required for the production of bean curd and therefore the production of bean curd has been considered to be unsuitable for mass production.
However, due to the fact that there had been a time when it was difficult to obtain magnesium chloride and also due to the excessively high reactivity of the magnesium chloride, the use of calcium sulfate or glucono delta lactone as a coagulant has begun several tens years ago and quite different types of bean curd from those made by the old and traditional production method have been placed in large quantities on the market.
Presently, the types of bean curd available in large quantities on the market can be divided broadly into three classes of so called cotton type bean curd of the rather tough kind, silk type bean curd of the soft kind and fill-in type bean curd of the kind filled in a sealed package.
In recent years, there has been an increasing voice for natural food and therefore the demand for soybean milk as a natural drink or a raw material for bean curd has been increasing. Also, while mass-produced inexpensive packaged bean curds have become available in these modern days, there has been a rapid growth in the demand for bean curd of the conventional type employing bittern and containing no artificial additive.
However, soybean milk made from soybeans has had a peculiar smell of soybean and spices, chemicals, etc., have been added to drown the smell of soybean, thus making the resulting soybean milk far from the one that can be considered as a natural drink.
Also, with the bean curd of the type employing the bittern, the reactivity of the bittern has been so high as mentioned previously that the coagulation process requires skill. As a result, the production of such bean curd by machinery has not been realized as desired and the production has been effected by a hand method, thereby supplying bean curd made on a small scale and hence expensive only to the local market.
In addition, the disposal of bean curd refuse resulting in the course of the production of bean curd has presented a problem in small-scale bean curd factories.
Moreover, due to the high reactivity of bittern, the production of silk type bean curd has been made only by using calcium sulfate and glucono delta lactone as coagulating agents.
Further, after the production of the bean curd, the long-distance transport has involved the danger of the bean curd getting out of shape during the transport due to it being so soft.